Migratory birds fly to far away areas during a particular time of the year. <br> Which of the following condition present in their habitat during that time are responsible for this? <br> i. Unavailable of food <br> ii. Extreme weather conditions <br> iii. Over crowding <br> iv. Lack of nesting areas

Question

$\begin{array}{1 1} (a)\; \text{ii and iii} \\ (b)\; \text{i and ii} \\ (c)\; \text{i and iv} \\ (d)\; \text{ii and iv} \end{array}$